Namesakes
Islamic Caliphs:
3 caliphs
Caliph Uthman ibn Affan 644-656 Rashidun 
Caliph Osman II (a.k.a. Uthman) 1618-1622 Ottoman
Caliph Osman III (a.k.a. Uthman) 1754-1757 Ottoman
Ottoman Sultans:
2 sultans, 1 bey
Bey Osman I (a.k.a. Uthman) 1281-1326
Sultan Osman II (a.k.a. Uthman) 1618-1622
Sultan Osman III (a.k.a. Uthman) 1754-1757